The present invention relates to an ultrasonic imaging apparatus for emitting an ultrasonic wave to an object to be examined and displaying echo signals reflected by the object as a tomographic image.
In a conventional ultrasonic imaging apparatus, a tomogram of the object can be displayed on a TV monitor in a range 50- to 100-mm wide and 200-mm deep, and can be enlarged up to 1.3 times.
However, the tomographic image displayed on the TV monitor cannot be properly observed with the conventional apparatus since a specific object portion (e.g., diseased portion) is often too small to observe accurately. For example, if a 2- to 3-mm portion of the object is to be observed on the TV monitor, it cannot be accurately discriminated, depending on a given resolution of the monitor. In this case, the portion can be enlarged for better diagnosis, even in the conventional apparatus. However, the magnification is predetermined, and the field of view is limited. In addition, when the portion is enlarged, the standard size tomographic image disappears from the screen and the position of the enlarged image is deviated from that in the standard size image. As a result, an operator or doctor cannot perform proper diagnosis.